The Challenge:

A homeowner in Brooklyn, NY contacted Zavza Seal after noticing water entering their basement during heavy rain. Although a waterproofing channel had already been installed, water continued to find its way into the basement.

Our inspection showed that the problem was not coming from the home’s foundation itself. Instead, water was entering from the narrow cavity between the customer’s wall and the neighboring property’s wall.

As rainwater traveled down from the neighbor’s side, it encountered small gaps and uneven surfaces inside the cavity. These obstructions redirected the water toward our customer’s foundation instead of allowing it to drain into the existing waterproofing channel.

Because the source of the leak was hidden inside the shared wall cavity, a standard crack repair would not have solved the problem.

Our Solution:

After carefully evaluating the water flow, our team developed a waterproofing solution designed to seal the entire cavity and guide the water directly into the existing drainage system.

The project included several steps.

First, we installed long threaded anchors at an upward angle from the waterproofing channel toward the neighboring wall. These anchors created a stable base for the next phase of the repair.

Next, we secured solid waterproofing strips across the cavity, creating a continuous surface that would direct water into the waterproofing channel instead of allowing it to spill toward the basement.

Once the strips were in place, we injected epoxy and urethane into the remaining gaps and voids. These materials filled hidden openings where water could pass through.

Finally, we applied a waterproofing paste across the entire surface of the waterproofing strips to create a durable, watertight barrier throughout the cavity.

The finished system now captures water entering from the neighboring side and safely directs it into the waterproofing channel for proper drainage.

The Results:

After the repair was completed, the homeowner had a fully sealed cavity between the two foundation walls. Water that previously bypassed the drainage system is now collected and redirected into the waterproofing channel as intended.

The project helped:

• Stop water from entering the basement through the shared wall cavity.
• Seal hidden gaps using epoxy and urethane injection.
• Create a continuous waterproof barrier between the two walls.
• Improve the performance of the existing waterproofing channel.
• Give the homeowner greater confidence during heavy rain.

By addressing the actual path the water was taking instead of simply treating the symptoms, Zavza Seal provided a long-lasting solution that protects the basement from future water intrusion.

Why This Repair Was Different?

Not every basement leak is caused by a foundation crack. In older homes, especially those built close together, water can travel through narrow spaces between neighboring buildings before finding a way inside.

In this Brooklyn project, understanding how the water was moving was the key to solving the problem. Rather than replacing the existing waterproofing system, our team improved it by sealing the hidden cavity and creating a controlled path for the water to follow.

This approach stopped the leak while preserving the existing drainage system, giving the homeowner a reliable waterproofing solution built to last.